Machines or equipment used at many production sites are typically controlled by control systems including controllers, such as programmable logic controllers (PLCs). A control system includes an input-output (IO) unit that receives an input signal from an external switch or sensor and outputs a signal to an external relay or actuator.
To satisfy control specifications, the control system has a variety of interrupts, including an IO interrupt, a shutdown interrupt, and a periodic interrupt. An IO interrupt implements interrupt processing in response to an input signal received from an external source. A shutdown interrupt implements interrupt processing in response to shutdown of power supplied to, for example, a PLC. A periodic interrupt implements interrupt processing executed in every predetermined period.
As techniques associated with interrupts, for example, Japanese Unexamined Patent Application Publication No. 2012-010216 (Patent Literature 1) describes an interrupt system including a host device and a peripheral device connected to each other with a network. Japanese Unexamined Patent Application Publication No. 2011-086120 (Patent Literature 2) describes a serial bus controller that transmits an interrupt signal for implementing a synchronization process to each relevant device at the same timing to reduce jitter of such interrupt signals for synchronization.